There is no default resolver implementation used for Spring
DispatcherServlets,
as an application might choose to parse its multipart requests itself. To define
an implementation, create a bean with the id "multipartResolver" in a
DispatcherServlet's
application context. Such a resolver gets applied to all requests handled
by that DispatcherServlet.

resolveMultipart

Parse the given HTTP request into multipart files and parameters,
and wrap the request inside a
MultipartHttpServletRequest object
that provides access to file descriptors and makes contained
parameters accessible via the standard ServletRequest methods.

Parameters:

request - the servlet request to wrap (must be of a multipart content type)

Returns:

the wrapped servlet request

Throws:

MultipartException - if the servlet request is not multipart, or if
implementation-specific problems are encountered (such as exceeding file size limits)